Nail coatings for cosmetic purposes, known variously as base coats, top coats, lacquers, varnishes, and enamels are the largest and most important group of manicure preparations. "The Nails", Chapter 22 in Harry's Cosmeticology, Wilkinson, J. B., and Moore, R. J., Eds., 7th Edition, pp 369-393. Chemical Publishing Company, Inc., New York, N.Y. 1982. Although nail coatings are generally collectively referred to as "nail polishes", such nomenclature is erroneous. Polishes contain fine abrasives that impart desirable characteristics, such as smoothness, based on friction created by buffing. Nail coatings, on the other hand, impart similar characteristics without friction due to components contained therein.
It is preferable that nail coatings be easily applied, dry rapidly and uniformly, convey a high luster upon drying, and be substantially non-toxic. The application process can be messy and time consuming. Thus, it is also desirable that such coatings be durable to avoid frequent applications. Other desirable characteristics of nail coatings include smooth and even flow on application and uniform drying without adverse surface artifacts.
The vast majority of nail coating systems currently in use contain either toluene or formaldehyde, or a combination of toluene and/or formaldehyde with aryl resins. Toluene and formaldehyde have an extremely unpleasant odor, are toxic by ingestion or absorption through the skin, and can easily sensitize the skin, leading to hypersensitivity. Aldehydes are also immunoreactive agents, which can promote inflammation and cause desiccation of vital tissue. Furthermore, toluene and formaldehyde have been recently recognized as carcinogens by CAL OSHA and other health and safety regulatory agencies (See, e.g., United States Department of Labor OSHA Standard Subpart Z 1910.1048). Thus, it is desirable to minimize or eliminate toluene and aldehydes, particularly formaldehyde, from nail coating formulations.
In part due to the inherent high volatility and enhanced evaporation coefficients of nail coatings, moisture and organic contaminants such as bacteria, molds, spores, viruses and fungi can become trapped on the nail surface and between the nail coating and the nail plate, resulting in polymicrobial infections of the nail plate and brittle, unsightly, disfigured nails. Onychomycosis is just one example of the myriad of microbial etiologies of nail disfigurement. Treatment of polymicrobial infections of the nail plate can require expensive, prolonged medical therapy, which is not always innocuous and can even be toxic. Moreover, such treatments often provide less than satisfactory cure rates and patient tolerance. From a commercial standpoint, professional nail technicians and consumers of professional nail care products and services recognize that lifting and chipping of artificial (e.g. acrylic) nails is exacerbated by organic contaminants that grow at the interface of the natural nail and the artificial nail, or the artificial nail-coating interface. In addition, organic contaminants between the surface of the natural nail and a lacquer coating can cause lifting, chipping and reduced adhesion of lacquer coatings.
U.S. Pat. No. 4,957,730 discloses an antimycotic nail varnish. The nail varnish comprises, as anti-mycotic agents, certain 1-hydroxy-pyridones. However, the 1-hydroxy-pyridones have limited application because they are effective against mycotic organisms, not bacteria. Thus, in order to treat bacterial infections, an antibacterial agent would need to be somehow incorporated into these formulations. U.S. Pat. No. 5,487,776 discloses an anti-fungal nail lacquer and method for use thereof. The anti-fungal nail lacquer contains, as an anti-fungal agent, griseofulvin. However, griseofulvin, like the 1-hydroxy-pyridones of U.S. Pat. No. 4,957,730, is an anti-fungal agent and an additional antibacterial agent is required in order to treat bacterial infections. Furthermore, the disclosure provides that about 25 to 75 percent of the griseofulvin will generally be in solution, while the remaining 75 to 25 percent will generally be in colloidal suspension.
While alcohols are commonly used as solvents in nail lacquer compositions, prolonged contact between many antimicrobial agents can result in diminished activity of the antimicrobial agent. Clearly it would be advantageous, for esthetic reasons and for consistency in application, to have a true solution of an antimicrobial agent in a nail lacquer composition. It would also be advantageous if a nail lacquer composition were developed that provided both treatment and prophylaxis against a broad spectrum of microorganisms.
Thus, there remains a need for prophylaxis against polymicrobial infections of the nail plate, including continuous prophylaxis against acquired organic contamination after the application of a nail coating. It is also desirable to minimize or eliminate aldehyde and ketone solvents, particularly formaldehyde, in nail coatings. The present invention is directed to these, as well as other, important needs.